Individual construction of vacuum bags for commerical uses is a time consuming process and is unreliable unless skilled persons are assigned to the task. The task is further complicated when the critical point of establishing the air-tight seal is at the point of fastening. Requiring the fastening contact to be air-tight limits the types of fastening and also requires that the fastening construction be done with careful skill.
Certain prior patents have approached the problem of establishing vacuum bags. U.S. Pat. Nos. 3,553,054 and 3,575,756 of L. Maus describe methods for vacuum bag manufacture of thermossetting resin-impregnated fabric layers into suitable forms. The vacuum bag membrane is stretched over the material being laminated. Tape is required to affix the vacuum bag membrane to the base upon which the material being laminated is placed. Thus the seal for the vacuum bag is established at the taped meeting of the vacuum bag membrane and the base. Individual taping is required for each use.
U.S. Pat. No. 3,861,977 of Wiley is a method of establishing a vacuum bag by sealing the vacuum bag directly to the product being molded. The vacuum bag is secured to the product by angle irons.
The air-tight seal herein is formed between ribbing and a stretchable material pulled taut over a raised ribbing. The ribbing is placed sufficiently within the point of fastening allowing for a variety of types of fastening. The fastening is at a point below the raised elevation of the ribbing allowing a secure air-tight seal.
Fasteners which are re-usable are used to fasten the stretchable material to the surface.
Constructing the air-tight seal at a point away from the point of fastening, allows for a variety of fastening devices. Also, careful attention is not needed at the point of fastening for all that need be accomplished by the fastening is pulling the stretchable material taut over the raised ribbing. Since this task is very basic, the employment of skilled personnel is not needed for the repeated use of the vacuum bag.